scholarly journals Low genetic variation in tolerance to defoliation in a long-lived tropical understorey palm

2018 ◽  
Author(s):  
Merel Jansen ◽  
Pieter A. Zuidema ◽  
Aad van Ast ◽  
Frans Bongers ◽  
Marcos Malosetti ◽  
...  
Keyword(s):  
Growth Rate ◽  
Genetic Variation ◽  
Leaf Area ◽  
Growth Rates ◽  
Compensatory Growth ◽  
Plant Performance ◽  
Evolutionary Adaptation ◽  
Strong Correlations ◽  
Growth Responses ◽  
Compensatory Responses

Defoliation is a ubiquitous stressor that can strongly limit plant performance. Tolerance to defoliation is often associated with compensatory growth. Genetic variation in tolerance and compensatory growth responses, in turn, play an important role in the evolutionary adaptation of plants to changing disturbance regimes but this issue has been poorly investigated for long-lived woody species. We quantified genetic variation in plant growth and growth parameters, tolerance to defoliation and compensatory responses to defoliation for a population of the understorey palm Chamaedorea elegans. In addition, we evaluated genetic correlations between growth and tolerance to defoliation. We performed a greenhouse experiment with 731 seedlings from 47 families with twelve or more individuals of C. elegans. Seeds were collected in southeast Mexico within a 0.7 ha natural forest area. A two-third defoliation treatment (repeated every two months) was applied to half of the individuals to simulate leaf loss. Compensatory responses in specific leaf area, biomass allocation to leaves and growth per unit leaf area were quantified. We found that growth rate was highly heritable and that plants compensated strongly for leaf loss. However, genetic variation in tolerance, compensation, and the individual compensatory responses was low. We found strong correlations between family mean growth rates in control and defoliation treatments. We did not find indications for growth-tolerance trade-offs: genetic correlation between tolerance and growth rate were not significant. The low genetic variation in tolerance and compensatory responses observed here suggests a low potential for evolutionary adaptation to changes in damage or herbivory, but high ability to adapt to changes in environment that require different growth rates. The strong correlations between family mean growth rates in control and defoliation treatments suggest that performance differences among families are also maintained under stress of disturbance.

Compensatory growth responses to defoliation and light availability in two native Mexican woody plant species

2010 ◽  
Vol 26 (2) ◽  
pp. 163-171 ◽  
Author(s):  
Horacio Salomón Ballina-Gómez ◽  
Silvia Iriarte-Vivar ◽  
Roger Orellana ◽  
Louis S. Santiago
Keyword(s):  
Growth Rate ◽  
Leaf Area ◽  
Resource Availability ◽  
Compensatory Growth ◽  
Continuum Hypothesis ◽  
Light Availability ◽  
Rate Model ◽  
Growth Responses ◽  
Resource Model ◽  
Resource Gradient

Abstract:Defoliation, often caused by herbivory, is a common cause of biomass loss for plants that can affect current and future growth and reproduction. There are three models that predict contrasting compensatory growth responses of plants to herbivory and resource availability: (1) Growth rate model, (2) Compensatory continuum hypothesis and (3) Limiting resource model. The predictions of these three models were tested on the tree Brosimum alicastrum and the liana Vitis tiliifolia. Seedlings were subjected to three levels of experimental defoliation (0%, 50% and 90% leaf removal) along a light resource gradient (1%, 9% and 65% of full sun). In both species, defoliation significantly increased leaf production rate and relative growth rate of leaf area, but not of biomass. Net assimilation rate was the strongest driver of biomass growth in both species, but leaf area ratio and specific leaf area were also important in B. alicastrum. Compensatory responses of leaf area growth in B. alicastrum were significantly greater in higher than lower light availability, consistent with the compensatory continuum hypothesis predictions, but in contrast to the growth rate model predictions. The limiting resource model offered an explanation for all possible experimental outcomes by directly considering the effects of environmental differences in resource availability.

Growth responses of six bryophyte species to different light intensities

1993 ◽  
Vol 71 (5) ◽  
pp. 661-665 ◽  
Author(s):  
Emmanuel Rincón
Keyword(s):  
Growth Rate ◽  
Light Intensity ◽  
Growth Rates ◽  
Growth Analysis ◽  
Total Chlorophyll ◽  
Light Conditions ◽  
Growth Responses ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Plastic Responses

The growth responses of Brachythecium rutabulum, Eurhynchium praelongum, Lophocolea bidentata, Plagiomnium undulatum, Pseudoscleropodium purum, and Thuidiurn tamariscinum, growing under seven different light conditions, were determined in a 36-day laboratory experiment. Biomass production, relative growth rate, chlorophyll content, and morphological plastic responses (bending of the shoots) were determined following initial and final harvests. All species achieved greater biomass as irradiance increased. This trend was also observed in the relative growth rates, which were higher as irradiance increased, for all the bryophytes investigated. All species except L. bidentata showed an increased elevation of the shoot as irradiance decreased. Total chlorophyll was higher in all species at the lowest irradiance level, but no clear differences were observed in the ratios of chlorophyll a to b for all the species. Key words: grassland bryophytes, light intensity, growth analysis, plasticity.

Studies of grain production in Sorghum bicolor (L. Moench). V.* Effect of planting density on growth and yield

1975 ◽  
Vol 26 (1) ◽  
pp. 31 ◽  
Author(s):  
KS Fischer ◽  
GL Wilson
Keyword(s):  
Growth Rate ◽  
Grain Yield ◽  
Leaf Area ◽  
Growth Rates ◽  
Dry Matter ◽  
Leaf Growth ◽  
Crop Growth ◽  
Area Index ◽  
Crop Growth Rate ◽  
Net Assimilation

Growth analysis was applied to grain sorghum (cv. RS610) grown at low, medium and high population densities, i.e. 14,352, 143,520 and 645,836 plants ha-1 respectively. The medium densities had two arrangements of plants, square (S) and rectangular (R). Crop growth rates, inflorescence growth rates, leaf area indices, net assimilation rates and leaf growth rates were calculated from growth functions of plant dry matter and leaf area over time. Differences in crop growth rate between populations in the early stages were attributed to leaf area development—specifically to the initial leaf area (dependent on seedling number) and not to differences in leaf growth rates. Peak crop growth rates were 15.0, 27.5, 26.0 and 45.8 g m-2 day-1 for the low, medium (S), medium (R) and high populations respectively.The large difference between the growth rates of the medium (S) and the high populations was not explained by differences in the amount of radiation intercepted. Although leaf area indices were 4.6 and 10.2 respectively for the two populations, both canopies intercepted almost all of the noon radiation. Light extinction coefficients were 0.45 and 0.29 respectively. The relationship between net assimilation rate and leaf area index was such that for comparable leaf area indices above 2, plants at higher densities showed greater improvement in yield per unit increment in leaf area index. A maximum grain yield of 14,250 kg ha-1 was obtained at the high population density as a result of higher dry matter production, but a similar harvest index to that of the crops grown at the other densities. Inflorescence growth rate (g m-2 day-l) slightly exceeded crop growth rate in the latter part of grain filling, which indicated that there was some retranslocation to the grain of previously assimilated material. The maximum grain yield represents an efficiency of utilization of short-wave solar radiation during crop life of 2.5 x 10-6g cal-1. *Part IV, Aust. J. Agric. Res., 26: 25 (1975).

scholarly journals Growth responses of light demanding and shade tolerant peat swamp forest saplings to elevated CO2

2021 ◽  
Vol 42 (3(SI)) ◽  
pp. 735-743
Author(s):  
M.N.L. Wahidah ◽  
◽  
M.S. Nizam ◽  
C.M.Z. Che Radziah ◽  
W.A. Wan Juliana ◽  
...  
Keyword(s):  
Growth Rate ◽  
Leaf Area ◽  
Relative Growth Rate ◽  
Elevated Co2 ◽  
Co2 Concentration ◽  
Growth Responses ◽  
Swamp Forest ◽  
Relative Growth ◽  
Peat Swamp Forest ◽  
Elevated Atmospheric Co2

Aim: To determine the growth responses of two peat swamp forest species, Shorea platycarpa, a shade-tolerant slow-growing species and Macaranga pruinosa, a light-demanding fast-growing species under elevated atmospheric CO2 concentration. Methodology: The saplings of both species were grown in a shade house at ambient (400±50 µmol mol-1) and in an open roof ventilation greenhouse at elevated atmospheric CO2 concentration 800±50 µmol mol-1 for seven months. The temperature in both environments ranged between 25-33°C with 55–60% sunlight transmittance and the saplings were thoroughly watered twice a day. Plants growth measurements were estimated at frequent intervals. Saplings biomass characteristics were examined using destructive methods after seven months of treatment and non-destructive method was used for determination of leaf area. Results: Elevated CO2 enhanced all the growth characteristics in M. pruinosa with a significant increase was observed particularly on both height and diameter relative growth rate and biomass characteristics. The height relative growth rate and leaf area were significantly reduced under elevated CO2 in S. platycarpa but did not affect the shoot or root diameter and biomass significantly. A positive correlation (r =0.77, p>0.05) between stem biomass and basal diameter for plants under elevated CO2 was recorded for M. pruinosa, but not in S. platycarpa. Both species showed negative correlation (S. platycarpa; r = -0.53, M. pruinosa; r = -0.46, p>0.05) between stem growth and stem biomass at elevated CO2. Interpretation: These results unveiled profound effects of elevated CO2 on the growth of light-demanding species M. pruinosa, while shade-tolerant species S. platycarpa was not relatively affected by elevated CO2. This underscored the necessity to analyse different species performance to elevated CO2, thereby improving the ability to predict tropical swamp forest ecosystem responses to rising CO2.

The effect of feeding hay in autumn or winter on the liveweight gain and carcase characteristics of beef steers

1981 ◽  
Vol 21 (108) ◽  
pp. 12
Author(s):  
GR Saul ◽  
AJ Clark
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Crude Protein ◽  
Compensatory Growth ◽  
Beef Steers ◽  
Average Quality ◽  
Average Growth ◽  
Grazing System ◽  
Digestible Organic Matter ◽  
Effect Of Feeding

Each year from 1975 to 1977, three groups of six beef steers, 9 months old, were stocked at 2.6 ha-l and managed under one of the following treatments: (1 ) Pasture only (PO), no supplementary feeding, (2) Winter feeding (WF) ; pasture hay was cut from 33% of the grazed area, stored and fed back the following winter while the steers were at pasture. (3) Autumn deferment (AD) ; 33% of the grazed area was cut for hay and rolled using an Econ fodder roller. For 8-11 weeks after the opening rains, the steers were fed a complete hay ration of fodder rolls while confined to a tenth of the grazed area. Thereafter the steers grazed the whole area. The AD and WF hay averaged 11% crude protein, and 56% digestible organic matter. The growth rate of all groups during autumn was similar and averaged 0.1 5 kg day-1. During winter, the average growth rates of the PO, WF and AD groups were 0.26, 0.44 and 0.61 kg day-1, respectively. In spring the respective growth rates were 1.09, 0.81 and 0.77 kg day1 and the overall growth rates were 0.40, 0.37 and 0.42 kg day-1. The results show that when using average quality hay produced within the grazing system, AD is more effective than WF in increasing the winter liveweight gains of steers. However, the yearly beef production from each system was similar due mainly to compensatory growth by the PO steers in spring.

Endogenous gibberellin content does not correlate with photoperiod-induced growth changes in strawberry petioles

1999 ◽  
Vol 26 (4) ◽  
pp. 359 ◽  
Author(s):  
Nadine J. Wiseman ◽  
Colin G. N. Turnbull
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Gas Chromatography Mass Spectrometry ◽  
Growth Responses ◽  
Selected Ion Monitoring ◽  
Growth Changes ◽  
Gibberellin A1 ◽  
Gibberellin Content ◽  
Short Days ◽  
Ga Content

We have examined whether gibberellins (GAs) mediate photoperiodic growth responses in strawberry (Fragaria × ananassa) by measuring GA content and GA metabolism in petioles with accurately defined growth rates. Gibberellin A1 , GA8 , GA19 , GA20 , GA29 , GA34 , and tentatively GA17 , were identified by gas chromatography–mass spectrometry, and GA4 was detected by selected ion monitoring. Although petiole growth rates were reduced within 2 d of a long-day to short-day transfer, we found no consistent changes in GA content until 8 d, when GA1 , GA8 , GA29 and GA34 were reduced by about two-fold in short days. GA20 concentration was always low regardless of age or treatment, typically 10-fold less than GA1 and 40-fold less than GA19 . Application of paclobutrazol (25 g plant–1 ) reduced growth rate by 43%, somewhat greater than the effect of short days (23%), but resulted in a six-fold decrease in GA1 content, much greater than the maximum two-fold effect of short days. However, paclobutrazol-treated petioles in long and short days differed in growth rate by 30%, yet had no difference in GA1 content. [2H]GA19 and [2H]GA20 were metabolised to GA1 , GA8 and GA29 , although conversion of GA19 was slow. GA4 was converted to GA 34 but not to GA1 or GA8 . Photoperiod had little effect on any of these metabolic steps. For the following reasons, we suggest that the photoperiod growth response is not mediated primarily through altered GA concentrations: (1) a lack of a rapid photoperiod effect on GA concentrations or metabolism, (2) changes in growth before or independent of changes in GA concentrations and (3) a normal photoperiod effect on growth in petioles with artificially lowered GA content.

The plane of nutrition and compensatory growth in pigs

1964 ◽  
Vol 6 (2) ◽  
pp. 227-236 ◽  
Author(s):  
D. W. Robinson
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Food Restriction ◽  
Growth Response ◽  
Compensatory Growth ◽  
Live Weight ◽  
Moderate Degree ◽  
Food Conversion ◽  
Large White ◽  
Food Conversion Efficiency

1. An experiment was carried out with forty individually-fed Large White × Wessex pigs to examine the growth rates of females (gilts) and castrated males after varying periods of time on a restricted plane of nutrition.2. Compensatory growth was made by pigs in all treatments when some restriction in the plane of nutrition had been previously imposed.3. The immediate growth response after the restriction ceased was directly related to the duration of the period of restriction.4. In pigs on a restricted scale of feeding to 80 lb. live-weight, no compensatory growth was observed until a later stage in growth, whereas pigs on a restricted scale for a much longer period to 160 lb. live-weight showed immediate and significant compensatory growth.5. In the periods immediately after the food restriction was lifted, gilts responded more than castrated males on all treatments.6. The effect on the overall growth rate from 45 to 200 lb. live-weight became progressively worse as the period of restriction was prolonged and in no case did the compensatory growth fully compensate for the setback suffered during restriction.7. There were no significant differences in overall food conversion efficiency and it appears that pigs with an even rate of gain and an interrupted growth rate may be equally efficient.8. There were no significant differences in carcass length or dressing-out percentage although a moderate degree of restriction up to 120 lb. live-weight improved grading results, these being related, to non-significant improvements i n food conversion and therefore possibly to a lower carcass fat content.

scholarly journals Contrasting growth responses to aluminium addition among populations of the aluminium accumulator Melastoma malabathricum

AoB Plants ◽  
2020 ◽  
Vol 12 (5) ◽  
Author(s):  
Khairil Mahmud ◽  
David F R P Burslem
Keyword(s):  
Growth Rate ◽  
Growth Medium ◽  
Growth Rates ◽  
Dry Mass ◽  
Nutrient Concentrations ◽  
Growth Responses ◽  
Relative Growth ◽  
Melastoma Malabathricum ◽  
Elemental Stoichiometry ◽  
Al Addition

Abstract Aluminium (Al) hyper-accumulation is a common trait expressed by tropical woody plants growing on acidic soils. Studies on Al accumulators have suggested that Al addition may enhance plant growth rates, but the functional significance of this trait and the mechanistic basis of the growth response are uncertain. This study aimed to test the hypothesis that differential growth responses to Al among populations of an Al accumulator species are associated with variation in biomass allocation and nutrient uptake. We conducted two experiments to test differential responses to the presence of Al in the growth medium for seedlings of the Al accumulator shrub Melastoma malabathricum collected from 18 populations across Peninsular Malaysia. Total dry mass and relative growth rate of dry mass were significantly greater for seedlings that had received Al in the growth medium than for control plants that did not receive Al, but growth declined in response to 5.0 mM Al addition. The increase in growth rate in response to Al addition was greater for a fast-growing than a slow-growing population. The increase in growth rate in response to Al addition occurred despite a reduction in dry mass allocation to leaves, at the expense of higher allocation to roots and stems, for plants grown with Al. Foliar concentrations of P, K, Mg and Ca increased in response to Al addition and the first axis of a PCA summarizing foliar nutrient concentrations among populations was correlated positively with seedling relative growth rates. Some populations of the Al hyper-accumulator M. malabathricum express a physiological response to Al addition which leads to a stimulation of growth up to an optimum value of Al in the growth medium, beyond which growth declines. This was associated with enhanced nutrient concentrations in leaves, which suggests that Al accumulation functions to optimize elemental stoichiometry and growth rate.

Studies on the productivity of tropical pasture plants. I. Growth analysis, photosynthesis, and respiration of Hamil grass and Siratro in a controlled environment

1968 ◽  
Vol 19 (1) ◽  
pp. 35 ◽  
Author(s):  
MM Ludlow ◽  
GL Wilson
Keyword(s):  
Growth Rate ◽  
Leaf Area ◽  
Growth Rates ◽  
High Growth ◽  
Net Assimilation Rate ◽  
Controlled Environment ◽  
Assimilation Rate ◽  
Relative Growth ◽  
Net Assimilation ◽  
Photosynthesis And Respiration

Hamil grass and Siratro were grown as single plants in pots in controlled environment cabinets at a temperature favouring high growth rates and with adequate water and mineral nutrients. Leaf areas and dry weights of plant parts were recorded in two experiments, to which some of the plants were common. In the first experiment, weekly samples until 4 weeks from sowing provided data for the calculation of relative growth rates, net assimilation rates, and leaf area ratios. The relative growth rate of Hamil grass was almost twice that of Siratro and appears to be the highest yet recorded for any plant. The higher growth rate for the grass resulted from a high net assimilation rate, although the leaf area ratio was lower. The second experiment used Watson and Hayashi's method, in which plants are kept in darkness for a varying number of days to separate net assimilation rate into photosynthetic and respiratory components. Data were collected at 2 and 4 weeks from sowing. The high net assimilation rate of the grass was shown to result from a higher photosynthetic rate, despite a much greater respiration rate than in the legume. The technique used for estimating photosynthesis and respiration is discussed in relation to some of the assumptions that it makes.

Compensation potential in six depleted groundfish stocks from the Northwest Atlantic

2016 ◽  
Vol 73 (2) ◽  
pp. 257-269 ◽  
Author(s):  
M. Joanne Morgan ◽  
Peter A. Shelton ◽  
Fernando González-Costas ◽  
Diana González-Troncoso
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Gadus Morhua ◽  
Reference Points ◽  
Sustainable Harvest ◽  
Northwest Atlantic ◽  
Compensatory Responses ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Potential Impact

Compensatory responses are important because they increase spawning stock biomass (SSB) growth rates in depleted fish populations. We analyze recruits per spawner (R/SSB) and spawners per recruit (SSB/R) data from six well-studied depleted, or depleted and recovering, Northwest Atlantic groundfish stocks for evidence of compensatory responses. All stocks had periods of high R/SSB at low SSB; however, R/SSB showed considerable variability, and significant compensatory responses were only found in two stocks. For compensation in SSB/R, relationships were significant for three of the stocks. We examined the potential impact of compensation in R/SSB and SSB/R on SSB growth rate and concluded that SSB/R could have a greater potential impact on enhancing SSB growth rate in depleted stocks. Overall, cod (Gadus morhua) populations showed greater compensation than flatfish, mainly due to the lower potential in flatfish to increase SSB/R. This suggests that cod are more resilient to overfishing than are flatfish. Estimates of population growth rate at low stock size, which ignore compensation in SSB/R, will underestimate maximum SSB growth rates. Compensation in both R/SSB and SSB/R should both be considered when evaluating stock productivity, sustainable harvest levels, and biological reference points.

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